Electronic systems and circuits have made a significant contribution towards the advancement of modern society and are utilized in a number of applications to achieve advantageous results. Numerous electronic technologies such as digital computers, calculators, audio devices, video equipment, and telephone systems have facilitated increased productivity and reduced costs in analyzing and communicating data, ideas and trends in most areas of business, science, education and entertainment. Frequently, these advantageous results are realized through the use of information stored on a memory media and manipulated by a processing device. The fabrication of memory devices often involves complex processes that require precise operations to achieve desired delicate balances.
Numerous electronic devices include processors that operate by executing software comprising a series of instructions for manipulating data in the performance of useful tasks. The instructions and associated data are typically stored in a memory at locations identified by a unique indicator or address. The ability to access a memory and transfer information quickly and conveniently usually has a significant impact on information processing latency and often limits the utility a device can provide. The configuration of a memory usually affects the speed at which memory locations are accessed.
Certain types of memories built upon flash memory technologies usually offer the potential for relatively fast information access. Flash memories typically include flash memory cells arranged in a matrix in which each cell is characterized by a voltage operating range. A charge level in a floating gate of the flash memory cell controls whether or not a flash memory cell turns “on” or “off” when a threshold voltage level within the operating range is applied to a gate of the flash memory cell. Flash memory arrays usually offer a number of desirable characteristics. Flash memories are typically non-volatile and can retain information even if power is turned off, allow random access to data and in-system programmability, and have the ability to withstand common shock vibrations and environmental conditions.
Integrated circuit fabrication usually involves multi-step processes that attempt to produce precise components that operate properly. Many integrated circuit processes involve repeated deposition and removal of material layers to fabricate components and it is often very difficult to achieve optimized results within requisite narrow tolerances. The multi-step processes also often include diffusion and implantation operations to create regions with particular electrical characteristics. These regions can be adversely impacted by subsequent process steps in a manner that significantly affects performance. In typical traditional processes, dopants are implanted directly into the silicon (Si), which causes damage in the Si. A high temperature thermal cycle is usually required to anneal out the damage. For example, high temperature annealing can result in diffusion region migration that adversely changes the characteristics of a source or drain junction (e.g., resistivity, drain induced barrier leakage, etc.).
Semiconductor integrated circuit manufacturing efforts are usually complicated by ever increasing demands for greater functionality. More complicated circuits are usually required to satisfy the demand for greater functionality. For example, there is usually a proportional relationship between the number of components included in an integrated circuit and the functionality, integrated circuits with more components typically provide greater functionality. However, including more components within an integrated circuit often requires the components to be densely packed in relatively small areas and reliably packing a lot of components in relatively small areas of an IC is usually very difficult.
One traditional focus for achieving greater densities has been directed towards reducing the size of individual components (e.g., transistors). The components of an integrated circuit are usually fabricated on a single silicon substrate and maintaining both the integrity of the system as a whole as well as the individual basic device characteristics is very important for proper operation. Proper relational characteristics are very helpful in achieving these objectives and without them there is a tendency for detrimental interactions to occur. Thus, it is important for integrated circuit fabrication technologies to provide an advantageous balance between component integrity and increased component density.
Transistor source and drain formation usually include a diffusion process. It is important for source and drain dopants to be accurately applied to ensure proper operation without defects. It is also desirable for the source and drain formation to be efficient and low cost. Diffusion of high quality dopants with the ability to provide shallow junctions can be challenging. Implantation is usually performed before CoSi formation in a typical memory cell formation process. The implantation energy usually has to be high to ensure the CoSi layer is above N+/P junction, which often results in a deeper junction and worse DIBL. Therefore, the ability to precisely form source and drain sections in a convenient and efficient manner is very important.